Primer composition

ABSTRACT

A primer composition comprises (A) an organosilicon compound of the general formula (1) ##STR1## wherein R represents an alkylene group having from 1 to 6 carbon atoms, R 1  represents a divalent hydrocarbon group having not less than 4 carbon atoms, R 2  &#39;s may be the same or different and independently represent an unsubstituted or substituted monovalent hydrocarbon group, a is 0 or 1, and b is 0, 1, 2 or 3, and (B) a catalyst for condensation of the organosilicon compound and (C) an organopolysiloxane resin.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a primer composition which ensures goodadhesion between an adherend formed with an electrodeposition coating onthe surface thereof and a room temperature curable silicone rubber bodyand is thus useful as a primer for sealants.

2. Description of the Prior Art

Silicone rubbers exhibit good heat resistance, cold resistance,weatherability and electric insulating properties, and have wide utilityin the fields of sealing materials for buildings, adhesive sealingmaterials, electric insulating materials, potting materials and thelike. Where strong adhesion is necessary between adherends and siliconerubbers as with sealants for buildings and adhesive sealing materials,usual practice is to pretreat the adherend with primers.

The primers employed for room temperature curable silicone rubbers whichare used as a sealant for buildings include, for example, compositionswhich comprise silane coupling agents and/or reaction products thereof,polyester resin and acrylic resins, and compositions which comprisephenyl group-containing siloxanes, alkyl silicates and chlorosilanes.

In recent years, acrylic resin paints or fluorine resin paints, whichexhibit good weatherability, chemical resistance, electric insulatingproperties and inflammability, have been applied by electropainting orspraying and widely used as a coating for outer walls of buildings.Accordingly, there has been a demand of development of primers whichhave good adhesion to the coating films, especially to the filmsobtained by the electropainting.

Japanese Laid-open Application No. 2-219885 proposes a primercomposition which comprises a hydroxyl group or alkoxy group-containingorganopolysiloxane, an amino group-containing silane and a titanic acidester. Japanese Laid-open Application No. 6-128553 proposes a primercomposition which comprises a hydroxyl group or alkoxy group-containingorganopolysiloxane, an organosilicon compound having an amino group andat least two alkoxy groups, an organosilicon compound having a mercaptogroup and at least two alkoxy groups, and an organotitanium and/ororganozirconium compound. Although adhesion to metals to be painted isimproved to some extent, it is not always satisfactory. Especially, theadhesion between an adherend such as an electropainted metal and a roomtemperature curable silicone rubber is not satisfactory.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a primercomposition which can overcome the problems of the prior art primercompositions and which is able not only to strongly adhere to adherendssuch as metals, glass, concrete and the like, but also to ensure strongbonding between adherends on which acrylic resins or fluorine resinshave been electropainted and silicone rubbers.

The above object can be achieved, according to the invention, by aprimer composition which comprises:

(A) an organosilicon compound of the general formula (1) ##STR2##wherein R represents an alkylene group having from 1 to 6 carbon atoms,R¹ represents a divalent hydrocarbon group having not less than 4 carbonatoms, R² 's may be the same or different and independently represent anunsubstituted or substituted monovalent hydrocarbon group, a is 0 or 1,and b is 0, 1, 2 or 3; and

(B) a catalyst for condensation of the organosilicon compound.

DETAILED DESCRIPTION OF THE INVENTION

(A) Organosilicon compounds

The organosilicon compounds used in the present invention arerepresented by the formula (1) and are an important component whichensures good adhesion imparted to the composition.

In the formula (1), R represents an alkylene group having from 1 to 6carbon atoms. Specific examples include --CH₂ --, --CH₂ CH₂ --, --CH₂CH₂ CH₂ --, --CH₂ CH₂ CH₂ CH₂ -- and the like, of which --CH₂ CH₂ -- ispreferred.

R¹ represents a divalent hydrocarbon group having not less than 4 carbonatoms, preferably 4 to 30 carbon atoms, and more preferably from 6 to 12carbon atoms. If the number of carbon atoms is less than 4, satisfactoryadhesion between an electropainted adherend and a silicone rubber maynot be attained. Examples of the divalent hydrocarbon group includephenylene group-containing divalent hydrocarbon groups such as ##STR3##and the like, and cyclohexylene group-containing divalent hydrocarbongroups such as ##STR4## and the like, linear alkylene groups of theformula, --(CH₂)_(n) -- wherein n is an integer of 4 or above such as--(CH₂)₄ --, --(CH₂)₈ --, --(CH₂)₁₂ -- and the like, and unsaturationbond-containing divalent hydrocarbon groups such as --CH═CH--CH═CH--. Ofthese, the phenylene group and the phenylene-group containing divalenthydrocarbon groups are preferred. If b is 0 or 1, R² 's may be the sameor different and represent a substituted or unsubstituted monovalenthydrocarbon group, preferably an alkyl group having from 1 to 4 carbonatoms, and more preferably methyl or ethyl. a is 0 or 1, preferably 0. bis 0 or an integer of 1 to 3, preferably 0 or 1.

Specific examples of the (A) component are those shown below: ##STR5##are preferred.

The condensation catalyst of the (B) component serves as a catalyst forcuring the organosilicon compound of the (A) component. This componentitself is taken in and becomes part of a final primer layer, therebyforming a strong film. The condensation catalysts include tin compounds,titanium compounds, zirconium compounds and aluminum compounds. Examplesof the catalyst include titanium tetraalkoxides of the formula, Ti(OR⁴)₄and/or partial hydrolyzates thereof, zirconium tetraalkoxides of theformula, Zr(OR⁴)₄ and/or partial hydrolyzates thereof, tintetraalkoxides of the formula, Sn(OR⁴)₄ and/or partial hydrolyzatesthereof, and aluminum trialkoxides of the formula, Al(OR⁴)₃ and/orpartial hydrolyzates thereof, in which R⁴ is as defined with respect toR² and preferably represents a monovalent hydrocarbon group having from1 to 4 carbon atoms.

Specific examples of the titanium alkoxides include titaniumtetramethoxide, titanium tetraethoxide, titanium tetrapropoxide,titanium tetraisopropoxide, titanium tetrabutoxide and the like, ofwhich titanium tetraethoxide is preferred. Examples of the zirconiumtetraalkoxides include zirconium tetramethoxide, zirconiumtetraethoxide, zirconium tetrapropoxide, zirconium tetraisopropoxide,zirconium tetrabutoxide and the like, of which zirconium tetraethoxideis preferred. Examples of the tin tetraalkoxides include tintetramethoxide, tin tetraethoxide, tin tetrapropoxide, tintetraisopropoxide, tin tetrabutoxide, tin tetra-t-butoxide and the like,of which tin tetra-t-butoxide is preferred. Examples of aluminumtrioxides include aluminum (III) ethoxide, aluminum (III) isopropoxide,aluminum (III) S-butoxide, aluminum (III) n-butoxide,mono-S-butoxyaluminum diisopropoxide and the like, of which aluminum(III) S-butoxide, aluminum (III) n-butoxide and mono-S-butoxyaluminumdiisopropoxide are preferred. These compounds may be used singly or incombination.

The (B) component should preferably be used in amounts of 5 to 500 partsby weight, more preferably from 10 to 200 parts by weight, per 100 partsby weight of the (A) component. If the amount is less than 5 parts byweight, there is some possibility that the resultant film is not alwayssatisfactory with respect to the strength and adhesion. Over 500 partsby weight, the film may become too hard to attain satisfactory adhesion.

In order to further improve the adhesion of the primer composition, itis preferred to add, as (C) component, an organopolysiloxane resin ofthe following average compositional formula (2) to the primercomposition

    R.sup.3.sub.c SiO.sub.4-c/2                                (2)

wherein each R³ independently represents an unsubstituted or substitutedmonovalent hydrocarbon group having, preferably from 1 to 10 carbonatoms, and c is a positive value of from 0.4 to 1.8.

Specific examples of the monovalent hydrocarbon group include alkylgroups such as methyl, ethyl, propyl and the like, alkenyl groups suchas vinyl allyl and the like, aryl groups such as phenyl, tolyl and thelike, cycloalkyl groups such as cyclohexyl, aralkyl groups such asbenzyl, phenylethyl and the like, and those groups mentioned abovewherein part or all of the hydrogen atoms in the groups are substitutedwith a halogen atom or a cyano group, e.g. chloromethyl,trifluoropropyl, cyanoethyl and the like. Of these, the alkyl and arylgroups are preferred. More preferably, methyl or phenyl is mentioned.

If c is a value smaller than 0.4, the resultant organopolysiloxanebecomes too hard and satisfactory adhesion will not develop. On theother hand, when c exceeds 1.8, the resultant product is, for example,diorganopolysiloxane such as silicone oil. This is not satisfactory withrespect to adhesion.

The organopolysiloxane resin of (C) component can be readily obtained byco-hydrolysis or hydrolysis of chlorosilanes or alkoxysilanes.Preferably, co-hydrolyzates of chlorosilanes or alkoxysilanes of theformulas, R³ ₂ SiX₂ and R₃ SiX₃ wherein R₃ is same as defined above, andX is chlorine or OR² in which R² is same as defined before, orco-hydrolyzates of chlorosilanes or alkoxysilanes of the formulas, R³ ₃SiX and SiX₄ wherein R₃ and X are, respectively, as defined above, areused. In the above formulas, the group represented by R³ is preferablymethyl or phenyl. When the chlorosilanes or alkoxysilanes of theformulas, R³ ₂ SiX₂ and R₃ SiX₃, are co-hydrolyzed, the resultantorganopolysiloxane resin consists of R³ ₂ SiO_(2/2) units (D units) andR³ SiO_(3/2) units (T units). With the co-hydrolysis of the compounds ofthe formulas, R³ ₃ SiX and SiX₄, the organopolysiloxane resin obtainedconsists of R³ ₃ Si_(1/2) units (M units) and SiO_(4/2) units (Q units).The ratio between the D and T units and the ratio between the M and Qunits are, respectively, so selected that c is within a range of 0.4 to1.8.

The organopolysiloxane resin usually has a hydroxyl group at both endsthereof.

The amount of the organopolysiloxane should preferably be in the rangeof from 10 to 900 parts by weight, more preferably from 30 to 300 partsby weight, per 100 parts by weight of the (A) component.

The primer composition of the invention should preferably be dissolvedin organic solvents in order to allow easy coating and workingoperations. The organic solvents used for this purpose are not criticalso far as they are able to dissolve the components of the primercomposition therein and are volatile in nature. Examples of suchsolvents include benzene, toluene, xylene, methanol, ethanol, isopropylalcohol, butanol, ethylene glycol monomethyl alcohol, acetone, methylethyl ketone, ligroin, ethyl acetate, hexane, dioxane, tetrahydrofuranand the like. These solvents may be used on their own or in admixture.

The concentration of the primer composition in an organic solvent shouldpreferably be within a range of 1 to 50 wt %. If the concentration isless than 1 wt %, adhesion may become unsatisfactory. On the other hand,when the concentration exceeds 50 wt %, coating and working operationsmay not proceed smoothly.

The primer composition of the invention is readily obtained by uniformlymixing the components (A) and (B) along with the component (C), ifnecessary.

Moreover, pigments, heat resistance improvers and other additives may beadded within ranges of amounts not impeding the purposes of theinvention.

The primer composition of the invention may be coated on adherends made,for example, of metals or synthetic resins by brushing or spraying,followed by air-drying for a time of five minutes to 24 hours,preferably from 10 minutes to 12 hours and adhesion to silicone rubber.Alternatively, after the air-drying, the coated composition may beheated to make a harder film, followed by adhesion to silicone rubber.

The primer composition of the invention can strongly bond together anadherend, on which an acrylic resin or fluorine resin has beenelectropainted, and a room temperature curable silicone rubber bodytogether. Accordingly, the composition is very useful as a primer forsilicone sealants used for buildings and electropainted buildingmaterials.

The present invention is more particularly described by way of examples,which should not be construed as limiting the invention. In theexamples, parts are by weight. Comparative examples are also described.

Examples 1 to 9 and Comparative Examples 1 to 6

Different primer compositions were prepared by uniformly mixingcomponents at mixing ratios indicated in Tables 1 and 2.

An aluminum plate on which an acrylic resin paint AG 300 (commercialname of Kansai Paint Co., Ltd.) had been electropainted and an aluminumplate on which a fluorine resin paint Dick Flow S (commercial name ofKansai Paint Co., Ltd.) were, respectively, provided as an adherend. Thesurfaces of these plates were each washed with toluene and applied witheach primer composition by brushing, followed by air-drying to form aprimer film. Subsequently, a room temperature curable silicone rubber ofthe condensation type (Sealant New 70 of Shin-Etsu Chemical Co., Ltd.)was applied onto the primer film surface and cured. After 14 days, theadhesion between the cured silicone rubber and each of the paintedaluminum plate was determined according to the method described inJIS-A-5758. The results are shown in Tables 3 and 4.

                                      TABLE 1                                     __________________________________________________________________________                                 Example                                                                       1  2  3  4  5  6  7  8  9                        __________________________________________________________________________     ##STR6##                    2.5                                                                              2.5                                                                              2.5                                                                              2.5                                                                              2.5                                                                              2.5                                                                               0  0  0                        ##STR7##                     0  0  0  0  0  0 2.5                                                                              2.5                                                                              2.5                      * methylphenylpolysiloxane resin                                                                           2.5                                                                              2.5                                                                              2.5                                                                              5.0                                                                              2.5                                                                              2.5                                                                              2.5                                                                              5.0                                                                              1.5                      titanium tetraethoxide        0 2.5                                                                               0 2.5                                                                              2.5                                                                              1.0                                                                              2.5                                                                              7.5                                                                               0                       zirconium tetraisopropoxide  2.5                                                                               0 2.5                                                                               0  0  0  0  0 2.5                      hexane                       100                                                                               0 50 100                                                                              100                                                                              100                                                                              100                                                                              50 100                      toluene                       0 100                                                                              50  0  0  0  0 50  0                       __________________________________________________________________________     * Cohydrolyzate of methyltrichlorosilane and methylphenyldichlorosilane       (corresponding to a resin of the aforeindicated formula (2) wherein c =       0.9).                                                                    

                                      TABLE 2                                     __________________________________________________________________________                                 Comparative Example                                                           1   2   3   4   5   6                            __________________________________________________________________________     ##STR8##                    2.5 0   0   0   0   2.5                           ##STR9##                    0   0   0   0   0   0                            H.sub.2 N(CH.sub.2).sub.2Si(OCH.sub.2 CH.sub.3).sub.3                                                      0   0   2.5 0   2.5 0                            HS(CH.sub.2).sub.3Si(OCH.sub.3).sub.3                                                                      0   0   0   2.5 2.5 0                            methylphenylpolysiloxane resin                                                                             2.5 2.5 2.5 2.5 2.5 0                             ##STR10##                   0   0   0   0   0   2.5                          titanium tetraethoxide       0   2.5 2.5 2.5 2.5 2.5                          zirconium tetraisopropoxide  0   0   0   0   0   0                            hexane                       100 0   0   0   0   0                            toluene                      0   100 100 100 100 100                          __________________________________________________________________________

                                      TABLE 3                                     __________________________________________________________________________                Example                                                           Adherend    1  2  3  4  5  6  7  8  9                                         __________________________________________________________________________    Acrylic resin                                                                        rubber                                                                             100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                       paint  breakage                                                               electropainted                                                                       (%)                                                                    aluminum plate                                                                       interfacial                                                                         0  0  0  0  0  0  0  0  0                                               breakage                                                                      (%)                                                                    Fluorine resin                                                                       rubber                                                                             100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                       paint  breakage                                                               electropainted                                                                       (%)                                                                    aluminum plate                                                                       interfacial                                                                         0  0  0  0  0  0  0  0  0                                               breakage                                                                      (%)                                                                    __________________________________________________________________________

                  TABLE 4                                                         ______________________________________                                                     Comparative Example                                              Adherend       1      2      3    4    5    6                                 ______________________________________                                        Acrylic resin                                                                          rubber     0      0    0    0   35   15                              paint    breakage                                                             electropainted                                                                         (%)                                                                  aluminum plate                                                                         interfacial                                                                             100    100  100  100  65   85                                       breakage                                                                      (%)                                                                  Fluorine resin                                                                         rubber     0      0    0    0   30   10                              paint    breakage                                                             electropainted                                                                         (%)                                                                  aluminum plate                                                                         interfacial                                                                             100    100  100  100  70   90                                       breakage                                                                      (%)                                                                  ______________________________________                                    

Examples 10 to 16 and Comparative Examples 7 to 13

Different primer compositions were further prepared by uniformly mixingcomponents at mixing ratios indicated in Tables 5 and 6.

Aluminum plates on which acrylic resin paints AG 300 and AG 200(commercial names of Kansai Paint Co., Ltd.) had been, respectively,electropainted, and an aluminum plate on which a fluorine resin paintDick Flow S (commercial name of Kansai Paint Co., Ltd.) were,respectively, provided as an adherend. The surfaces of these plates wereeach washed with toluene and applied with each primer composition bybrushing, followed by air-drying to form a primer film. Subsequently, aroom temperature curable silicone rubber of the condensation type(Sealant New 70 of Shin-Etsu Chemical Co., Ltd.) was applied onto theprimer film surface and cured. The adhesion between the cured siliconerubber and each of the painted aluminum plate after 14 days wasdetermined as an initial adhesion. Moreover, each sample was subjectedto an immersion test for 7 days wherein the sample was immersed in waterat 50° C. Thereafter, the adhesion of the immersed sample was determinedas an adhesion after immersion in water. These adhesions were determinedby the method described in JIS-A-5758. The results are shown in Tables 7and 8.

                                      TABLE 5                                     __________________________________________________________________________                                Example                                                                       10 11 12 13 14 15 16                              __________________________________________________________________________     ##STR11##                  2.5                                                                              0  2.5                                                                              2.5                                                                              2.5                                                                              2.5                                                                              2.5                              ##STR12##                  0  2.5                                                                              0  0  0  0  0                               titanium tetraethoxide      2.5                                                                              2.5                                                                              0  0  0  2  2                               zirconium tetraisopropoxide 0  0  2.5                                                                              0  0  0.5                                                                              0                               tin tetra-t-butoxide        0  0  0  2.5                                                                              0  0  0.5                             aluminum tri-s-butoxide     0  0  0  0  2.5                                                                              0  0                               hexane                      90 90 90 90 90 90 90                              isopropanol                 10 10 10 10 10 10 10                              __________________________________________________________________________

                                      TABLE 6                                     __________________________________________________________________________                                Comparative Example                                                           7  8  9  10 11 12 13                              __________________________________________________________________________     ##STR13##                  2.5                                                                              0  0  0  0  0  0                                ##STR14##                  0  0  0  0  0  0  0                               H.sub.2 NC.sub.3 H.sub.6 Si(OC.sub.2 H.sub.5).sub.3                                                       0  0  0  0  0  2.5                                                                              0                               H.sub.2 NC.sub.2 H.sub.4 NHC.sub.3 H.sub.6 Si(OCH.sub.3).sub.3                                            0  0  0  0  0  0  2.5                             titanium tetraethoxide      0  2.5                                                                              0  0  0  2.5                                                                              2.5                             zirconium tetraisopropoxide 0  0  2.5                                                                              0  0  0  0                               tin tetra-t-butoxide        0  0  0  2.5                                                                              0  0  0                               aluminum tri-s-butoxide     0  0  0  0  2.5                                                                              0  0                               hexane                      90 90 90 90 90 90 90                              isopropanol                 10 10 10 10 10 10 10                              __________________________________________________________________________

                                      TABLE 7                                     __________________________________________________________________________                    Example                                                       Adherend        10 11 12 13 14 15 16                                          __________________________________________________________________________    Acrylic resin paint                                                                    initial rubber                                                                       100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                         AG 300-  breakage (%)                                                         electropainted                                                                aluminum plate                                                                         initial                                                                               0  0  0  0  0  0  0                                                   interfacial                                                                   breakage (%)                                                                  rubber 100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                  breakage after                                                                immersion in                                                                  water (%)                                                                     interfacial                                                                           0  0  0  0  0  0  0                                                   breakage after                                                                immersion in                                                                  water (%)                                                            Acrylic resin paint                                                                    initial rubber                                                                       100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                         AG 200-  breakage (%)                                                         electropainted                                                                aluminum plate                                                                         initial                                                                               0  0  0  0  0  0  0                                                   interfacial                                                                   breakage (%)                                                                  rubber 100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                  breakage after                                                                immersion in                                                                  water (%)                                                                     interfacial                                                                           0  0  0  0  0  0  0                                                   breakage after                                                                immersion in                                                                  water (%)                                                            Fluorine resin                                                                         initial rubber                                                                       100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                         paint-   breakage (%)                                                         electropainted                                                                aluminum plate                                                                         initial                                                                               0  0  0  0  0  0  0                                                   interfacial                                                                   breakage (%)                                                                  rubber 100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                  breakage after                                                                immersion in                                                                  water (%)                                                                     interfacial                                                                           0  0  0  0  0  0  0                                                   breakage after                                                                immersion in                                                                  water (%)                                                            __________________________________________________________________________

                                      TABLE 8                                     __________________________________________________________________________                    Comparative Example                                           Adherend        7  8  9  10 11 12 13                                          __________________________________________________________________________    Acrylic resin paint                                                                    initial rubber                                                                        0  0  0  0  0 100                                                                              100                                         AG 300-  breakage (%)                                                         electropainted                                                                aluminum plate                                                                         initial                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                               0  0                                                   interfacial                                                                   breakage (%)                                                                  rubber  0  0  0  0  0  0  0                                                   breakage after                                                                immersion in                                                                  water (%)                                                                     interfacial                                                                          100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                  breakage after                                                                immersion in                                                                  water (%)                                                            Acrylic resin paint                                                                    initial rubber                                                                        0  0  0  0  0 100                                                                              100                                         AG 200-  breakage (%)                                                         electropainted                                                                aluminum plate                                                                         initial                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                               0  0                                                   interfacial                                                                   breakage (%)                                                                  rubber  0  0  0  0  0  0  0                                                   breakage after                                                                immersion in                                                                  water (%)                                                                     interfacial                                                                          100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                  breakage after                                                                immersion in                                                                  water (%)                                                            Fluorine resin                                                                         initial rubber                                                                        0  0  0  0  0 100                                                                              100                                         paint-   breakage (%)                                                         electropainted                                                                aluminum plate                                                                         initial                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                               0  0                                                   interfacial                                                                   breakage (%)                                                                  rubber 100                                                                               0  0  0  0 100                                                                              100                                                  breakage after                                                                immersion in                                                                  water (%)                                                                     interfacial                                                                           0 100                                                                              100                                                                              100                                                                              100                                                                               0  0                                                   breakage after                                                                immersion in                                                                  water (%)                                                            __________________________________________________________________________

Examples 17 to 23 and Comparative Examples 14 to 20

Different primer compositions were prepared by uniformly mixingcomponents at mixing ratios indicated in Tables 9 and 10.

Aluminum plates on which acrylic resin paints AG 300 and AG 200(commercial names of Kansai Paint Co., Ltd.) had been, respectively,electropainted, and an aluminum plate on which a fluorine resin paintDick Flow S (commercial name of Kansai Paint Co., Ltd.) were,respectively, provided as an adherend. The surfaces of these plates wereeach washed with toluene and applied with each primer composition bybrushing, followed by air-drying to form a primer film. Subsequently, aroom temperature curable silicone rubber of the condensation type(Sealant New 70 of Shin-Etsu Chemical Co., Ltd.) was applied onto theprimer film surface and cured. The adhesion between the cured siliconerubber and each of the painted aluminum plate after 14 days wasdetermined as an initial adhesion. Moreover, each sample was subjectedto an immersion test for 7 days wherein the sample was immersed in waterat 50° C. Thereafter, the adhesion of the immersed sample was determinedas an adhesion after immersion in water. These adhesions were determinedby the method described in JIS-A-5758. The results are shown in Tables11 and 12.

                                      TABLE 9                                     __________________________________________________________________________                      Example                                                                       17 18 19 20 21 22 23                                        __________________________________________________________________________     ##STR15##        2.5                                                                              0  2.5                                                                              2.5                                                                              2.5                                                                              2.5                                                                              2.5                                       H.sub.2 N(CH.sub.2).sub.2C.sub.6 H.sub.10Si(OCH.sub.3).sub.3                                    0  2.5                                                                              0  0  0  0  0                                         titanium tetraethoxide                                                                          2.5                                                                              2.5                                                                              0  0  0  2  2                                         zirconium tetraisopropoxide                                                                     0  0  2.5                                                                              0  0  0.5                                                                              0                                         tin tetra-t-butoxide                                                                            0  0  0  2.5                                                                              0  0  0.5                                       aluminum tri-s-butoxide                                                                         0  0  0  0  2.5                                                                              0  0                                         hexane            90 90 90 90 90 90 90                                        iospropanol       10 10 10 10 10 10 10                                        __________________________________________________________________________

                                      TABLE 10                                    __________________________________________________________________________                      Comparative Example                                                           14 15 16 17 18 19 20                                        __________________________________________________________________________     ##STR16##        2.5                                                                              0  0  0  0  0  0                                         H.sub.2 N(CH.sub.2).sub.2C.sub.6 H.sub.10Si(OCH.sub.3).sub.3                                    0  0  0  0  0  0  0                                         H.sub.2 NC.sub.3 H.sub.6 Si(OC.sub.2 H.sub.6).sub.3                                             0  0  0  0  0  2.5                                                                              0                                         H.sub.2 NC.sub.2 H.sub.4 NHC.sub.3 H.sub.6 Si(OCH.sub.3).sub.3                                  0  0  0  0  0  0  2.5                                       titanium tetraethoxide                                                                          0  2.5                                                                              0  0  0  2.5                                                                              2.5                                       zirconium tetraisopropoxide                                                                     0  0  2.5                                                                              0  0  0  0                                         tin tetra-t-butoxide                                                                            0  0  0  2.5                                                                              0  0  0                                         aluminum tri-s-butoxide                                                                         0  0  0  0  2.5                                                                              0  0                                         hexane            90 90 90 90 90 90 90                                        iospropanol       10 10 10 10 10 10 10                                        __________________________________________________________________________

                                      TABLE 11                                    __________________________________________________________________________                    Example                                                       Adherend        17 18 19 20 21 22 23                                          __________________________________________________________________________    Acrylic resin paint                                                                    initial rubber                                                                       100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                         AG 300-  breakage (%)                                                         electropainted                                                                aluminum plate                                                                         initial                                                                               0  0  0  0  0  0  0                                                   interfacial                                                                   breakage (%)                                                                  rubber 100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                  breakage after                                                                immersion in                                                                  water (%)                                                                     interfacial                                                                           0  0  0  0  0  0  0                                                   breakage after                                                                immersion in                                                                  water (%)                                                            Acrylic resin paint                                                                    initial rubber                                                                       100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                         AG 200-  breakage (%)                                                         electropainted                                                                aluminum plate                                                                         initial                                                                               0  0  0  0  0  0  0                                                   interfacial                                                                   breakage (%)                                                                  rubber 100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                  breakage after                                                                immersion in                                                                  water (%)                                                                     interfacial                                                                           0  0  0  0  0  0  0                                                   breakage after                                                                immersion in                                                                  water (%)                                                            Fluorine resin                                                                         initial rubber                                                                       100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                         paint-   breakage (%)                                                         electropainted                                                                aluminum plate                                                                         initial                                                                               0  0  0  0  0  0  0                                                   interfacial                                                                   breakage (%)                                                                  rubber 100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                  breakage after                                                                immersion in                                                                  water (%)                                                                     interfacial                                                                           0  0  0  0  0  0  0                                                   breakage after                                                                immersion in                                                                  water (%)                                                            __________________________________________________________________________

                                      TABLE 12                                    __________________________________________________________________________                    Comparative Example                                           Adherend        14 15 16 17 18 19 20                                          __________________________________________________________________________    Acrylic resin paint                                                                    initial rubber                                                                        0  0  0  0  0 100                                                                              100                                         AG 300-  breakage (%)                                                         electropainted                                                                aluminum plate                                                                         initial                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                               0  0                                                   interfacial                                                                   breakage (%)                                                                  rubber  0  0  0  0  0  0  0                                                   breakage after                                                                immersion in                                                                  water (%)                                                                     interfacial                                                                          100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                  breakage after                                                                immersion in                                                                  water (%)                                                            Acrylic resin paint                                                                    initial rubber                                                                        0  0  0  0  0 100                                                                              100                                         AG 200-  breakage (%)                                                         electropainted                                                                aluminum plate                                                                         initial                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                               0  0                                                   interfacial                                                                   breakage (%)                                                                  rubber  0  0  0  0  0  0  0                                                   breakage after                                                                immersion in                                                                  water (%)                                                                     interfacial                                                                          100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                  breakage after                                                                immersion in                                                                  water (%)                                                            Fluorine resin                                                                         initial rubber                                                                        0  0  0  0  0 100                                                                              100                                         paint-   breakage (%)                                                         electropainted                                                                aluminum plate                                                                         initial                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                                                               0  0                                                   interfacial                                                                   breakage (%)                                                                  rubber 100                                                                               0  0  0  0 100                                                                              100                                                  breakage after                                                                immersion in                                                                  water (%)                                                                     interfacial                                                                           0 100                                                                              100                                                                              100                                                                              100                                                                               0  0                                                   breakage after                                                                immersion in                                                                  water (%)                                                            __________________________________________________________________________

What is claimed is:
 1. A primer composition which comprises:(A) anorganosilicon compound of the general formula (1) ##STR17## wherein Rrepresents an alkylene group having from 1 to 6 carbon atoms, R¹represents a divalent hydrocarbon group having not less than 4 carbonatoms, R² 's may be the same or different and independently represent anunsubstituted or substituted monovalent hydrocarbon group, a is 0 or 1,and b is 0, 1, 2 or 3; (B) a catalyst for condensation for theorganosilicon compound; and (C) an organopolysiloxane resin of thefollowing average compositional formula

    R.sup.3.sub.c SiO.sub.4-c/2

wherein each R³ independently represents an unsubstituted or substitutedmonovalent hydrocarbon group, and c is a positive value of from 0.4 to1.8.
 2. A primer composition according to claim 1, wherein R¹ represents--CH₂ CH₂ --.
 3. A primer composition according to claim 1, wherein R¹is a phenylene group or a phenylene group-containing divalenthydrocarbon group.
 4. A primer composition according to claim 1, whereineach R² independently represents an alkyl group having from 1 to 4carbon atoms.
 5. A primer composition according to claim 1, wherein a iszero and b is 0 or
 1. 6. A primer composition according to claim 1,wherein said organosilicon compound consists essentially of a compoundof the formula ##STR18##
 7. A primer composition according to claim 1,wherein said organosilicon compound consists essentially of a compoundof the formula ##STR19##
 8. A primer composition according to claim 1wherein said catalyst becomes part of a film obtained from saidcomposition and is at least one member selected from the groupconsisting of titanium tetraalkoxides of the formula, Ti(OR⁴)₄, andpartial hydrolyzates thereof, zirconium tetraalkoxides of the formula,Zr(OR⁴)₄, and partial hydrolyzates thereof, tin tetraalkoxides of theformula, Sn(OR⁴)₄, and partial hydrolyzates thereof, and aluminumalkoxides and partial hydrolyzates thereof wherein each R⁴ is same asR².
 9. A primer composition according to claim 1, wherein said catalystis present in an amount of from 5 to 500 parts by weight per 100 partsby weight of said organosilicon compound.
 10. A primer compositionaccording to claim 1, wherein said composition is dissolved in a solventtherefor at a concentration of 1 to 50 wt %.
 11. A primer compositionaccording to claim 1, wherein said composition is dissolved in a solventtherefor at a concentration of 1 to 50 wt %.
 12. A primer compositionaccording to claim 1, wherein said organopolysiloxane is present in anamount of 10 to 900 parts by weight per 100 parts by weight of saidorganosilicon compound.